This invention relates to devices and methods for supporting tubing.
Tubing is utilized in many industrial installations for carrying pneumatic and hydraulic process and control fluids, process chemicals, particulates, and the like. Examples of such tubing are shown in O'Brien/Ametek TRACEPAK brochure QLT-TPBR-03, dated 20 Mar. 2012 and incorporated by reference herein. As shown in this brochure, tubing may be jacketed or unjacketed and may be bundled in various configurations. The bundles are typically round, with tubing clustered around a central long axis, or flat, with tubing arranged with long axes generally in a common plane. As used herein, “tubing” includes both individual tubes and tubing bundles, unless a more limited meaning is clearly indicated.
Numerous systems for carrying cable are known. An example, used for carrying telecommunications cable, is described in Caveney et al., U.S. Pat. No. 7,520,476.
In many situations, including chemical plants and oil platforms, process tubing and electrical cables must be strung over considerable distances. They are presently supported and contained in either an open or closed cable tray. Such cable trays are well known in the field. Ladder-type cable trays and mesh-type cable trays are particularly common. Examples are described in Rinderer, U.S. Pat. No. 6,313,405, Dooley, U.S. Pat. No. 5,465,929, Davis, et al., U.S. Pat. No. 8,424,814, and Boone, U.S. Pat. No. 8,215,592. Cable trays are typically installed before cables and tubing are; the cable trays define pathways through the facility for the cables and tubing.
Present cable tray systems carrying cable and tubing have several problems.
Frequently, space in a cable tray is at a premium. Therefore, the cables and tubing are not kept as neat and accessible as is desirable, and sometimes not everything fits.
Tubing is generally stiffer than cable. Typically, tubing needs to be supported every few feet. Six foot (3′-8′) horizontal reaches and fifteen foot (5′-20′) vertical reaches are regarded as standard for many common types of tubing, the allowable span varying by tube diameter, wall thickness, and material. Cable is typically supported on 3″ to 18″ spacings with a ladder-type cable tray and smaller spacings with a mesh cable tray. Therefore, although the tubing does not need to be supported over as short a span as cable, it must share the heavier cable trays necessary to support the cable.
Further, when bent free-form, or by hand, the tubing does not bend on as small a radius as cable, while when bent with a mandrel it may bend on a smaller radius than the cable. Therefore, undesirable compromises and accommodations must be made. Sometimes, the tubing must be bent around too tight a radius, and therefore kinking is a constant danger. Other times to make a tight turn the tubing is spliced, a pre-formed curved section being fit between two straight sections in order to make the small-radius turn required by the cable tray. The splicing introduces field installation complexity. It also risks difficult-to-detect and difficult-to-repair leakage problems and corrosion problems. Other times the cable tray is made with a larger turning radius than would be needed for the cable, thereby making the cable runs longer and more invasive of space than necessary.
Additional bends may be required simply to bring the tubing out of the cable tray.
Also, cable and tubing are not always traveling between the same points. For example, both may be feeding an instrument, but the fluid in the tubing may be coming from a fluid source that is remote from the electrical source feeding the cable.